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neilhunt avatar image
neilhunt asked

Phoenix 12/1200 underperforming in DC-AC-DC configuration

I have a camper van setup, with dual AGM vehicle batteries charged by high power alternators, and a separate house battery bank, which I also wish to charge from the vehicle alternators from time to time. I am trying to use a Phoenix 12/1200 to take the vehicle alternator power (Transit high power 250A dual alternator) to 120v to drive a Multiplus 12/3000 as "shore power" to charge the 4x100Ah Battleborn LiFePO house batteries. I was hoping for 7.5A of 120V from about 85A of DC input, but I cannot get anywhere close to that.

In testing, just driving a resistive electric convection heater, it will drive 500W, but in the 900W setting it goes into "overload" immediately. Even at 500W, it gets to thermal shutdown (two flashes on the red LED) after a couple of minutes - this with the inverter flat on the van floor in open space at 40F ambient.

In using the Phoenix to drive the Muiltiplus shore power 120V input, I can only get 3.5A x 120V reliably; at 4A x 120V the Phoenix goes into thermal shutdown after about 30 seconds, and at 7.5A it shuts down immediately in overload. I have of course verified that shore power from a household 15A or 30A outlet, or a campground 15A, drives the Multiplus just fine as expected.


Is the power factor of the Multiplus input so offset that the Phoenix is never going to work?

Why is the Phoenix going into thermal shutdown with a 500W resistive load (PF1.0, I assume)?

Is there a different model that might work to get me to the 7.5A x 120V lowest setting for the Multiplus charger input?

Does it help to use Multiplus "Dynamic Current Limit" and/or "Weak AC" settings?


Thanks


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2 Answers
kevgermany avatar image
kevgermany answered ·

Is the problem the phoenix or the alternators? Might be you have smart alternators and they're messing the phoenix around.

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neilhunt avatar image neilhunt commented ·
Unlikely, I think, because when the engine is off, for a short while, power comes from two AGM vehicle batteries, which presumably is quite clean, and I observe the same symptoms.
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Jmarc avatar image
Jmarc answered ·

I would suspect the unfiltered alternator current is causing the issue.

If I understand you do not have a battery between the alternator and the 12/1200 inverter. The Alternator current is rectified. Because the load is light the diodes are creating large harmonics. I am not familiar with the internal architecture of the Inverter but transformers are very susceptible to overheating when high harmonics are present. For test just add a battery on the input of the inverter and see if it is the same.

The real question is why are you making it so complicated.. Why not just directly charging your Battleborn batteries? Use a good regulator such as the Wakespeed WS500 to protect your batteries.

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neilhunt avatar image neilhunt commented ·
No, there are dual AGM batteries filtering the alternator current. I erroneously omitted the detail for simplicity. In fact, when the engine is off, it's JUST the dual AGM batteries, until the 30 minute timeout elapses, or the vehicle battery voltage falls below threshold. In that time, I can see the same symptoms exhibited. The WS500 looks like it would subsume functionality that the vehicle alternator controller already performs, and would probably not be compatible with normal vehicle operation (since the alternators are not dedicated to the house battery charging application, but also maintain the separate vehicle power.
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kleszczewo avatar image kleszczewo neilhunt commented ·
Have you solved your problem and if so, how?


Thank you

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